1. Field of the Invention
The invention relates in general to the field of microfluidic devices and methods of fabrication thereof. In particular, it is directed to microfluidic devices provided with interconnects.
2. Description of the Related Art
Microfluidics generally refers to microfabricated devices, which are used for pumping, sampling, mixing, analyzing and dosing liquids. Prominent features thereof originate from the peculiar behavior that liquids exhibit at the micrometer length scale (see Brody J. P., Yager P., Goldstein R. E., and Austin R. H., Biotechnology at low Reynolds Numbers, Biophys. J. 1996, pp. 3430-3441, 71, and Knight J. B., Vishwanath A., Brody J. P. and Austin R. H., Hydrodynamic Focusing on a Silicon Chip: Mixing Nanoliter in Microseconds, Phys. Rev. Lett. 1998, pp. 3863-3866, 80). Flow of liquids in microfluidics is typically laminar. Volumes well below one nanoliter can be reached by fabricating structures with lateral dimensions in the micrometer range. Reactions that are limited at large scales (by diffusion of reactants) can be accelerated (see Squires T. M. and Quake S. R. Microfluidics: Fluid physics at the nanoliter scale, Rev. Mod. Phys. 2005, pp. 977-1026, 77). Finally, parallel streams of liquids can possibly be accurately and reproducibly controlled, allowing for chemical reactions and gradients to be made at liquid/liquid and liquid/solid interfaces (Kenis P. J. A., Ismagilov R. F. and Whitesides G. M., Microfabrication Inside Capillaries Using Multiphase Laminar Flow Patterning, Science, 1999, pp. 83-85, 285). Microfluidics are accordingly used for various applications in life sciences.
Many microfluidic devices have user chip interfaces and closed flow paths. Closed flow paths facilitate the integration of functional elements (e.g. heaters, mixers, pumps, UV detectors, valves, etc.) into one device while minimizing problems related to leaks and evaporation.
Liquids processed within microfluidic devices are generally introduced using fluidic interconnects. However, such interconnects may not be suitable for all applications.
For example, a solution developed in N. H. Bings et al., Anal. Chem., 1999, pp. 3292-3296, 71 (15), relies on holes partially drilled into glass and fused silica inserted therein. However, the obtained interconnect is manifestly not suitable for high mechanical stress.
Another solution (see e.g., C. Chiou et al., J. Micromech. Microeng., 2004, 1484, 14) consists of inserting a capillary into a Teflon casing, the latter being in turn glued into a drilled hole. Yet, this solution requires a complex, expensive assembly.
Still another solution (see e.g., A. Puntambekar et al., J. Micromech. Microeng., 2002 pp. 35-40, 12) is to use a composite tube-locking system using polymer flanged inserts. However, this solution involves a complex assembly, composite material, and is expensive.
Furthermore, each of the above solutions is labor intensive. For the sake of completeness, other solutions have been developed. See, e.g., D. Sabourin et al., Microfluidics & Nanofluidics, 2010, pp. 87-93, vol. 9, no. 1; T. Thorsen et al., Science, 2002, pp. 580-584, Vol. 298 no. 5593; C. F. Chen et al., 2009, 9(1):50-5, Lab Chip; D. M. Hartmann et al., 2008, pp. 609-616, Lab on a Chip, 8.
Such solutions, however, are not suitable for many applications. These solutions are too complex or too specific, not suitable for several materials such as glass and silicon, or labor intensive, etc.
Finally, what is perhaps the most widely used solution relies on commercially available ports (see e.g., Upchurch Scientific) that are glued onto the microfluidic device, see, e.g., www.idex-hs.com/. However, this solution results in a large footprint and gives rise to substantial dead volumes. It further requires aligning a port over a hole, which may be time consuming and require an instrument for alignment.